High-energy batteries, e.g., Na/NiCl.sub.2 or Na/S batteries, operate at temperatures between 250.degree. C. and 400.degree. C. These batteries are composed of individual tubular cells. The individual cells of one battery are to be maintained at the same temperature in order for the internal resistances of the cells to be the same. Different internal resistances would lead to different loads on the individual cells and consequently to different states of charge and discharge of the cells. Nonuniformities in the states of charge within the battery may lead to a reduction of the service life of the battery.
During a discharge cycle of such batteries, the inner areas of the battery in particular are heated more strongly than the outer ones, because heat dissipates via the housing. During charging, the cells which are arranged closest to the electric heater in particular have a higher temperature than the cells that are located at a greater distance.
The internal resistance leads to evolution of heat within the battery during discharge. This can be explained on the basis of the example of a 27 kWh battery with a voltage of 150 V and a capacity of 180 Ah: During a 2-hour discharge, i.e., discharge with a current of 90 A, it is necessary to continuously remove a waste power of ca. 2 kW. Part of the power loss can be accommodated by the thermal capacity of the battery, and the rest must be removed from the battery by means of a cooling system.
For example, various possibilities of cooling such batteries are described in the documents German Offenlegungsschriften Nos. DE-OS 32,47,969, 26,10,222, and 28,35,550. It is common to all these suggestions that the coolant sweeps past along the cells, and the heat is thus exchanged on the entire surface of the cell. These arrangements make little contribution to achieving temperature equalization between the individual cells of the battery. The temperature equalization, which takes place only very slowly, leads to nonuniform loads. Another disadvantage of these cooling devices is their complicated nature. For example, a special distribution system is installed in the battery according to the application in order to achieve uniform guidance of air along the cells. The distribution of air within the individual canals between the cells cannot be accurately calculated and must be optimized experimentally. If the conditions change within the battery (e.g., due to a change in the removal of heat via the walls of the battery), the air distribution must again be optimized in order to again ensure uniform temperature distribution. It is also necessary to redesign the geometry, e.g., of a distributor plate, each time the design is changed.